Lighter than air (LTA) platforms are enjoying renewed interest in a variety of applications. In addition to traditional uses such as advertising and promotion, there is increased interest in LTA platforms for both civil and military Intelligence, Surveillance, Reconnaissance, and Communications (ISR&C) applications.
The long endurance and low fuel consumption rates inherent in LTA systems are attractive attributes for persistent airborne ISR&C applications. An increasing demand for LTA platforms to provide a significant time-on-station capability, whether they are tethered aerostats or mobile airships, places increasing energy demands on long term power for both its payload and propulsion energy system. Current propulsion and electric power systems that rely on fossil fuels provide both limited transit range and time-on-station. The same is true for batteries as well as conventional fuel cell powered systems. As a result of these limitations, the full endurance potential of LTA ISR&C systems has been difficult to realize. Recent LTA designs have included renewable energy sources such as solar cells (i.e., photovoltaics) to enhance both mobile LTA platform range and time-on-station performance. Photovoltaic solutions can provide additional power to propulsors and payloads, but have their own limitations which include conversion efficiencies, restriction to daylight operations, and weather and weight issues.
There is a need for an energy source for fixed and mobile LTA platforms that can provide significant power for both propulsion (i.e., transit and station keeping) and payload systems.